Catheterization of vascular and other passageways in the body is a well known technigue used to accomplish a variety of tasks, including draining fluids from the body, introducing fluids (such as imaging fluids) into the passageways, performing repair procedures (such as angioplasty) and so forth.
The uses and desired uses of catheters is ever growing, owing at least in part to the attractiveness of being able to accomplish certain invasive tasks that otherwise would reguire surgery or sometimes even open heart surgery. Catheter procedures in lieu of surgery typically are less traumatic to the patient, and often reduce or eliminate many of the risks associated with surgery. Moreover, catheter procedures usually are much cheaper than surgery, if for no other reason that in-hospital recovery time is often significantly reduced or eliminated.
For example, as an alternative to cardiac coronary artery bypass surgery, balloon catheters have been used in coronary angioplasty for opening narrowed (atherosclerotic) coronary arteries. In such a procedure, a guidewire is advanced into the artery, followed by a balloon catheter. When a section of the artery is encountered that has been narrowed by plague deposits (a stenosis or lesion) the balloon is properly positioned (as determined by conventional radiological imaging) and then inflated. The balloon dilates the narrowed section of the artery, compressing the plague and slightly stretching the artery to widen the blood passageway. The balloon is then deflated, and may be advanced to another stenosis, or removed upon completion of the desired procedure. Detailed descriptions of such procedures may be found in, e.g., G. Jang. Angioplasty (1986).
Beyond angioplasty, catheters are also useful for providing a secure passageway through which small devices may be delivered to remote locations in the body. There are many desired uses for such catheters, however, that heretofore have been impossible or impractical due to the size of the device desired to be delivered through a passageway. The size of such devices is necessarily limited by the internal diameter of the catheter, and the size of the catheter in turn is limited by the internal diameter (and other factors, such as tortuosity, atherosclerotic plague, etc.) of the passageway itself.
This problem is compounded by the fact that often the patient needing a particular procedure may be advanced in age, which often means that the passageway may be somewhat more tortuous than in a younger patient. Moreover, in the case of arteries, the atherosclerotic process may have irregularly narrowed the arteries with artherosclerotic plagues.